Many printers in recent years are connected to a communication network and provided with a network printer function to receive image data from another apparatus such as a personal computer (PC) connected to the communication network and output an image. Further, multi-function apparatuses have been commercialized in which printers are provided with a plurality of functions such as a copying function to capture an image recorded on a sheet as image data by scanning it, form an image based on the captured image data and output the image, a facsimile function to transmit and receive image data to and from an external facsimile by use of facsimile communication, and a transmission function to transmit the captured image data to an external apparatus. In order to perform the image data processing in each function without stagnation, printers having such advanced multifunction are provided with storing means such as a hard disk for storing information such as image data and have a parallel processing function to successively store the accepted information while successively processing the information already stored in the storage image.
To the printers as described above, many PCs can be connected through the communication network, so that a plurality of users can provide an image output instruction. For this reason, there is a possibility that the images outputted onto recording sheets on instructions from a plurality of users are mixed together in the image discharge part and carried away by a wrong user by mistake. Therefore, a technology has been developed such that when receiving an image output job transmitted from a PC, the printer stores the job and waits without performing the image output and after the user inputs an output instruction by directly operating the printer, the printer outputs the image. Japanese Patent Application Laid-Open No. 60-25385 discloses a technology such that a password is transmitted together with image data from a PC to the printer, the printer stores the image data and waits, and in case that the user inputs the correct password by directly operating the printer, the printer outputs the image. Moreover, among such printers, products have been developed that have a function to back up information associated with the processing on standby in order that even when the power is turned off while the processing is on standby, the image output can be performed after the power is turned on again.
There are cases where information handled by printers includes confidential information such as documents including trade secrets, and security measures are necessary for the information stored in the storing means by the printer. In particular, in the case of a printer in which the image data is stored until the correct password is inputted as disclosed in Japanese Patent Application Laid-Open No. 60-25385, in case that the function to back up the information associated with the processing on standby is provided, the information is not deleted but is stored even after the power is turned off. For this reason, information such as image data can be taken out to the outside, for example, by reading out the information from an external apparatus or detaching the storing means, so that it is difficult to maintain the confidentiality of the information being handled.